I'm still surprised Sussman describes the 2000s as a "new" job whereas to me it's just mediocre soil from an unstable industry. Mucking around is not engineering.. it's alchemy.
Of course, it's often pointed out, "Well, if you write in Scheme (or C or Java or whatever) then you're not writing in assembly language, much less machine language, so you already don't understand everything." There's certainly truth there, but, to me, going from, expertise writing code in a high-level programming language to, gluing together libraries that you kinda-sorta understand, feels like a bigger leap in what you do or do not understand than going from assembly language to Python.
It's interesting that Sussman kind of lumps together "uncertain software libraries" into the same category as machine control robustness (e.g. hysteresis). I never thought of it that way but I guess in practice it's all just "stuff", those libraries are just another piece of your program's environment like any other.
Ability to deal / reflect with unknowns for engineering is of great value, but so far I've never seen that in office.